1// tLodGroup.h 
2// 
3// This unit implements scene LOD groups. LOD groups basically specify what model to use based on a size threshold. 
4// The threshold is based on screen-size, not distance. This is much more correct as it allows narrow camera FOVs 
5// without things looking pixelated. 
6// 
7// Copyright (c) 2006, 2017 Tristan Grimmer. 
8// Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby 
9// granted, provided that the above copyright notice and this permission notice appear in all copies. 
10// 
11// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL 
12// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, 
13// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN 
14// AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 
15// PERFORMANCE OF THIS SOFTWARE. 
16 
17#pragma once 
18#include <Foundation/tList.h> 
19#include "Scene/tObject.h" 
20namespace tScene 
21{ 
22 
23 
24class tLodParam 
25{ 
26public: 
27 tLodParam() { } 
28 tLodParam(const tChunk& chunk) { Load(chunk); } 
29 virtual ~tLodParam() { } 
30 
31 void Save(tChunkWriter&) const; 
32 void Load(const tChunk&); 
33 
34 uint32 ModelID = 0; 
35 
36 // The threshold is the proportion of screen width at which the LOD swap should occur. Doing it this way makes it 
37 // respect the camera FOV and does not tie it to screen resolution. The runtime can decide to consider the current 
38 // screen resolution if it likes. A value of 1.0 means that the object takes up the entire screen, 0.5 means half 
39 // the screen. The values are NOT restricted to [0.0, 1.0]. It is valid to have values > 1.0. If a runtime object 
40 // takes up less room than the threshold then the ModelID should not be used. The biggest lod info threshold value 
41 // that is less than the current percent is the right one. 
42 float Threshold = 0.0f; 
43}; 
44 
45 
46class tLodGroup : public tObject 
47{ 
48public: 
49 tLodGroup() : tObject(), LodParams() { } 
50 tLodGroup(const tChunk& chunk) : tObject(), LodParams() { Load(chunk); } 
51 virtual ~tLodGroup() { } 
52 
53 void Load(const tChunk&); 
54 void Save(tChunkWriter&) const; 
55 void Clear() { tObject::Clear(); LodParams.Empty(); } 
56 int GetNumLodInfos() const { return LodParams.GetNumItems(); } 
57 
58 // This call will sort all the lod params from highest threshold to lowest. 
59 void Sort() { LodParams.Sort(ThresholdCompare); } 
60 tItList<tLodParam> LodParams; 
61 
62private: 
63 // Implements a > b so the list is sorted in descending order. 
64 inline static bool ThresholdCompare(const tLodParam& a, const tLodParam& b) { return (a.Threshold > b.Threshold) ? true : false; } 
65}; 
66 
67 
68} 
69